FPS Drop Doown excessively!

[pollo]

Hi all!

I've been experiencing this for a while; somebody knows why my fps excessively drop down when Im near smoke/blood/dust/(...) effects?

This also happened when I installed directx10 in my old windows xp, but not before it so I don't think it is a pc problem... Could be Dx?

Screenshot here!

Without FX:





With FX (sometimes my fps drop down to 50 or 60):



Max fps when I'm out of map (it often gets to 1000)




Ty in advance

PS: I don't know where do I Put this kind of post... xD